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  • Job queue manager with RPC interface

    - by admr
    I need a job queue manager that I can control over the Internet. It should be able to execute and stop processes, check on their status (ideally notice and execute some code when a process exits), respond to commands and also be able to report back to a server. Background: I have a GWT application that allows to create jobs to execute on a cloud instance (currently EC2). I want to push a "job packet" (data for a process to operate on etc) to S3, start a Linux EC2 instance (or use one that's already running), and tell a job manager on the instance to execute that job (possibly parallel to other jobs). It should then pull the "job packet" from S3, run a process that operates on that data and report back to the server that is running the server part of my GWT application with some information (e.g. exit code, stdout, stderr). If I have to write e.g. stdour/err to a file from the process and read that file, that's OK too. I would really like the manager to be "close" to the processes it runs, meaning I want to avoid using something like Runtime.exec from the JDK. It seems like I would have to do that if I used Quartz for example. I'm fine with the calls in both directions being asynchronous. I'm fine with any reasonable technology for the calls as long as I can easily build an interface for that in my GWT server side (e.g. HTTP requests to a servlet over SSL would be nice and trivial). The job manager does not need to have a very sophisticated queueing system. Running several processes either sequentially or in parallel should be fine. Determining how much compute time a process received during its lifetime would be nice (AFAIK, this might be challenging). I did not yet find any existing software that does this, including http://java-source.net/open-source/job-schedulers. I suspect I might have to build an RPC interface (with authentication etc, of course) around a job manager; maybe use something like Apache Commons Exec. In that case, I would prefer Java or Python for the job manager part. I would be happy to hear suggestions for either the former or latter scenario!

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  • Killing Mysql prcoesses staying in sleep command.

    - by Shino88
    Hey I am connecting a MYSQL database through hibernate and i seem to have processes that are not being killed after they are finished in the session. I have called flush and close on each session but when i check the server the last processes are still there with a sleep command. This is a new problem which i am having and was not the case yesterday. Is there any way i can ensure the killng of theses processes when i am done with a session. Below is an example of one of my classes. public JSONObject check() { //creates a new session needed to add elements to a database Session session = null; //holds the result of the check in the database JSONObject check = new JSONObject(); try{ //creates a new session needed to add elements to a database SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory(); session = sessionFactory.openSession(); if (justusername){ //query created to select a username from user table String hquery = "Select username from User user Where username = ? "; //query created Query query = session.createQuery(hquery); //sets the username of the query the values JSONObject contents query.setString(0, username); // executes query and adds username string variable String user = (String) query.uniqueResult(); //checks to see if result is found (null if not found) if (user == null) { //adds false to Jobject if not found check.put("indatabase", "false"); } else { check.put("indatabase", "true"); } //adds check to Jobject to say just to check username check.put("justusername", true); } else { //query created to select a username and password from user table String hquery = "Select username from User user Where username = :user and password = :pass "; Query query = session.createQuery(hquery); query.setString("user", username); query.setString("pass", password); String user = (String) query.uniqueResult(); if(user ==null) { check.put("indatabase", false); } else { check.put("indatabase", true); } check.put("justusername", false); } }catch(Exception e){ System.out.println(e.getMessage()); //logg.log(Level.WARNING, " Exception", e.getMessage()); }finally{ // Actual contact insertion will happen at this step session.flush(); session.close(); } //returns Jobject return check; }

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  • Large Scale VHDL techniques

    - by oxinabox.ucc.asn.au
    I'm thinking about implimenting a 16 bit CPU in VHDL. A simplish CPU. ADD, MULS, NEG, BitShift, JUMP, Relitive Jump, BREQ, Relitive BREQ, i don't know somethign along these lines Probably all only working with 16bit operands. I might even cut it down and use only a single operand and a accumulator. With Some status regitsters, Carry, Zero, Neg (unless i use a Accumlator), I know how to design all the parts from logic gates, and plan to build them up from first priciples, So for my ALU I'll need to 'build' a ADDer, proably a Carry Look ahead, group adder, this adder it self is make up oa a couple of parts, wich are themselves made up of a couple of parts. Anyway, my problem is not the CPU design, or the VHDL (i know the language, more or less). It's how i should keep things organised. How should I use packages, How should I name my processes and port maps? (i've never seen the benifit of naming the port maps, or processes)

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  • Obtain Update Table Lock at start of Stored Procedure in SQL Server

    - by Jim Hurne
    I'm writing a SQL Server stored procedure in which I want to lock a table for update before executing the body of the stored procedure. I don't want to prevent other processes from reading the table, but I do want to prevent other processes updating the table. Here is my first attempt: CREATE PROCEDURE someProcedure BEGIN SET TRANSACTION ISOLATION LEVEL READ COMITTED BEGIN TRANSANCTION SELECT COUNT(*) FROM TheTable WITH (UPDLOCK, TABLOCK) -- Pause procedure so that we can view the locks with sp_lock WAITFOR DELAY '00:15' -- Do stuff COMMIT END When I execute the stored procedure, and invoke sp_lock, I see that the table is indeed locked. However, it's locked with an Exclusive lock instead of an update lock: spid | dbid | ObjId | IndId | Type | Resource | Mode | Status ------------------------------------------------------------------ 63 | 10 | 233208031 | 0 | TAB | | X | GRANT How can I get an update (U) lock instead?

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  • Distinct rand() sequences yielding the same results in an expression

    - by suszterpatt
    Ok, this is a really weird one. I have an MPI program, where each process has to generate random numbers in a fixed range (the range is read from file). What happens is that even though I seed each process with a different value, and the numbers generated by rand() are different in each process, the expression to generate the random numbers still yields the same sequence between them. Here's all relevant code: // 'rank' will be unique for each process int rank; MPI_Comm_rank(MPI_COMM_WORLD, &rank); // seed the RNG with a different value for each process srand(time(NULL) + rank); // print some random numbers to see if we get a unique sequence in each process // 'log' is a uniquely named file, each process has its own log << rand() << " " << rand() << " " << rand() << std::endl; // do boring deterministic stuff while (true) { // waitTimeMin and waitTimeMax are integers, Max is always greater than Min waitSecs = waitTimeMin + rand() % (waitTimeMax - waitTimeMin); log << "waiting " << waitSecs << " seconds" << std::endl; sleep(waitSecs); // do more boring deterministic stuff } Here's the output of each process, with 3 processes generating numbers in the range [1,9]. process 1: 15190 28284 3149 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds process 2: 286 6264 3153 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds process 3: 18151 17013 3156 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds So while rand() clearly generates different numbers, the expression to calculate waitSecs still evaluates to the same sequence on all processes. What's even weirder: if I run the program with the same parameteres again, only the first 3 random numbers will change, the rest of the "random" sequence will be exactly the same in each run! Changing the range of numbers will obviously produce a different result from this one, but the same parameters always yield the same sequence, between processes and between executions: except for the first 3 numbers. Just what the hell is going on here?

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  • Redirect application's graphical output in Windows Vista/7 (with DWM)

    - by puri
    I want to create a desktop manager that takes informations of all running applications including states and screenshots to display and manipulate them in my virtual space (probably in 3D). It can be considered as another layer of abstraction on top of Windows itself. Because many native Windows Vista/7 features like Flip 3D and Live Thumbnails are able to show each window's activities in real-time e.g. video keeps playing in taskbar's thumbnail, I think DWM allows an application to redirect its output to somewhere else or some special processes are able to collect other applications' graphical outputs (maybe of child processes only). Has Microsoft released a set of public APIs to do so? If not, is it technically possible? And is it easier if I limit my scope to just .NET applications with WPF?

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  • simple process rollback question

    - by OckhamsRazor
    hi folks! while revising for an exam, i came across this simple question asking about rollbacks in processes. i understand how rollbacks occur, but i need some validation on my answer. The question: my confusion results from the fact that there is interprocess communication between the processes. does that change anything in terms of where to rollback? my answer would be R13, R23, R32 and R43. any help is greatly appreciated! thanks!

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  • PHP Sessions - Locking and Sharing questions

    - by Nuno Peralta
    Hi, I would like to know if it is possible to read $_SESSION attributes without locking it. Currently, session_start() locks SESSION, that means other PHP processes will wait until it is unlocked. But, some processes just want to get some $_SESSION variables, not to write on them. Is that possible to implement some function like session_get(string $id) which doesn't lock SESSION? Also, it is possible to share SESSIONs between browsers, once the user is logged in the same account, for example, using session_id('shared_vars_of_'.$userid). But, is that secure? Is this discouraged? Thanks, Nuno

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  • Adding x11vnc as a Solaris SMF service

    - by rojanu
    I am trying add x11vnc as SMF service but cannot get service to start. I tried googling but couldn't find anything that could help me. Here is the startup script #!/sbin/sh # # Copyright (c) 1995, 1997-1999 by Sun Microsystems, Inc. # All rights reserved. # #ident "@(#)x11vnc 1.14 06/11/17 SMI" case "$1" in 'start') #/usr/local/bin/x11vnc -geometry 1280x1024 -noshm -display :0 -ncache 10 -noshm -shared -forever -o /tmp/vnc_remote.log -bg /usr/local/bin/x11vnc -unixpw -ncache 10 -display :0 -noshm -shared -forever -o /tmp/vnc_remote.log ;; 'stop') /usr/bin/pkill -x -u 0 x11vnc ;; *) echo "Usage: $0 { start | stop }" ;; esac exit 0 and here is the manifest file <?xml version='1.0'?> <!DOCTYPE service_bundle SYSTEM '/usr/share/lib/xml/dtd/service_bundle.dtd.1'> <service_bundle type='manifest' name='vnc'> <service name='application/x11vnc' type='service' version='0'> <create_default_instance enabled='true'/> <single_instance/> <dependency name='docusp' grouping='require_all' restart_on='none' type='service'> <service_fmri value='svc:/milestone/multi-user-server:default'/> </dependency> <exec_method name='start' type='method' exec='/lib/svc/method/x11vnc' timeout_seconds='0'> <method_context/> </exec_method> <exec_method name='stop' type='method' exec=':true' timeout_seconds='10'> <method_context/> </exec_method> <stability value='Evolving' /> <property_group name='startd' type='framework'> <propval name='ignore_error' type='astring' value='core,signal'/> </property_group> </service> </service_bundle> and the log file Usage: /lib/svc/method/x11vnc { start | stop } [ Nov 16 19:35:52 Method "start" exited with status 0 ] [ Nov 16 19:35:52 Stopping because all processes in service exited. ] [ Nov 16 19:35:52 Executing stop method (:kill) ] [ Nov 16 19:35:52 Executing start method ("/lib/svc/method/x11vnc") ] Usage: /lib/svc/method/x11vnc { start | stop } [ Nov 16 19:35:52 Method "start" exited with status 0 ] [ Nov 16 19:35:52 Stopping because all processes in service exited. ] [ Nov 16 19:35:52 Executing stop method (:kill) ] [ Nov 16 19:35:52 Executing start method ("/lib/svc/method/x11vnc") ] Usage: /lib/svc/method/x11vnc { start | stop } [ Nov 16 19:35:52 Method "start" exited with status 0 ] [ Nov 16 19:35:52 Stopping because all processes in service exited. ] [ Nov 16 19:35:52 Executing stop method (:kill) ] [ Nov 16 19:35:52 Restarting too quickly, changing state to maintenance ] Any Ideas?

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  • Multiprocessing Bomb

    - by iKarampa
    I was working the following example from Doug Hellmann tutorial on multiprocessing: import multiprocessing def worker(): """worker function""" print 'Worker' return if __name__ == '__main__': jobs = [] for i in range(5): p = multiprocessing.Process(target=worker) jobs.append(p) p.start() When I tried to run it outside the if statement: import multiprocessing def worker(): """worker function""" print 'Worker' jobs = [] for i in range(5): p = multiprocessing.Process(target=worker) jobs.append(p) p.start() It started spawning processes non-stop, without any way of to terminating it. Why would that happen? Why it did not generate 5 processes and exit? Why do I need the if statement?

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  • Get Janrain to work with Sproutcore?

    - by weng
    Since Sproutcore is not dependent on the backend server to render pages, I'm struggling on how to get it working with Janrain. In one of the login processes of Janrain a HTTP request is sent to a backend server that processes the information and render a logged in page to the user. Since I'm using Sproutcore and don't have a backend server but using CouchDB to serve Sproutcore I wonder how I am going to implement Janrain successfully. Even if I'm using a backend server like Node.js I'm still not sure how to implement Janrain. Has anyone implemented Janrain in a Sproutcore app?

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  • How to force programs out of swap file when a resources-intensive batch finishes?

    - by sharptooth
    We use employees' desktops for CPU-intensive simulation during the night. Desktops run Windows - usually Windows XP. Employees don't log off, they just lock the desktops, switch off their monitors and go. Every employee has a configuration file which he can edit to specify when he is most likely out of office. When that time comes a background program grabs data for simulation from the server, spawns worker processes, watches them, gets results and sends them to the server. When the time specified by the employee elapses simulation stops so that normal desktop usage is not interfered. The problem is that simuation consumes a lot of memory, so when the worker processes run they force other programs into the swap file. So when the employee comes all the programs he left are luggish and slow until he opens them one by one so that they are unswapped. Is there a way the program can force other programs out of swap file when it stops simulation so that they again run smoothly?

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  • C++ Asymptotic Profiling

    - by Travis
    I have a performance issue where I suspect one standard C library function is taking too long and causing my entire system (suite of processes) to basically "hiccup". Sure enough if I comment out the library function call, the hiccup goes away. This prompted me to investigate what standard methods there are to prove this type of thing? What would be the best practice for testing a function to see if it causes an entire system to hang for a sec (causing other processes to be momentarily starved)? I would at least like to definitively correlate the function being called and the visible freeze. Thanks

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  • internet explorer, google chrome injection

    - by Volim Te
    I wrote code that injects a function in Internet Explorer/Chrome but it doesn't work with these processes. Basically, it fills one big structure with all the APIs my function needs, strings, and other data, then it opens a process to get a handle, virtualallocex to allocate enough memory to store a function and structure there, and it writes the function and the structure in allocated memory. It then runs createremotethread there with the function as a starting address and structure as parameter. It works all great with calc/notepad/winamp processes but I have problems with browser injection. I'm wondering what could it be, I'm using these APIs. x.xCreateFile x.xWriteFile x.xCloseHandle x.xSleep x.xVirtualAlloc x.xVirtualFree x.xMessageBox x.xLoadLibrary x.xShellExecute Is it because browsers are protected now and they're running with lowest privileges?

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  • how much concurrent http request can erlang handle

    - by user209123
    I am developing a application for benchmarking purposes, for which I require to create large number of http connection in a short time, I created a program in java to test how much threads is java able to create, it turns out in my 2GB single core machine, the limit is variable between 5000 and 6000 with 1 GB of memory given to JVM after which it hits outofmemoryerror with heap limit reached. It is suggested around that erlang will be able to generate much more concurrent processes, I am willing to learn erlang if it is capable of solving the problem , although I am interested in knowing can erlang be able to say generate somewhere around 100000 processes which are essentially http requests waiting for responses, in a matter of few seconds without reaching any limit like memory error etc.,

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  • Task vs. process, is there really any difference?

    - by DASKAjA
    Hi there, I'm studying for my final exams in my CS major on the subject distributed systems and operating systems. I'm in the need for a good definition for the terms task, process and threads. So far I'm confident that a process is the representation of running (or suspended, but initiated) program with its own memory, program counter, registers, stack, etc (process control block). Processes can run threads which share memory, so that communication via shared memory is possible in contrast to processes which have to communicate via IPC. But what's the difference between tasks and process. I often read that they're interchangable and that the term task isn't used anymore. Is that really true?

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  • Improving HTML scrapper efficiency with pcntl_fork()

    - by Michael Pasqualone
    With the help from two previous questions, I now have a working HTML scrapper that feeds product information into a database. What I am now trying to do is improve efficiently by wrapping my brain around with getting my scrapper working with pcntl_fork. If I split my php5-cli script into 10 separate chunks, I improve total runtime by a large factor so I know I am not i/o or cpu bound but just limited by the linear nature of my scraping functions. Using code I've cobbled together from multiple sources, I have this working test: <?php libxml_use_internal_errors(true); ini_set('max_execution_time', 0); ini_set('max_input_time', 0); set_time_limit(0); $hrefArray = array("http://slashdot.org", "http://slashdot.org", "http://slashdot.org", "http://slashdot.org"); function doDomStuff($singleHref,$childPid) { $html = new DOMDocument(); $html->loadHtmlFile($singleHref); $xPath = new DOMXPath($html); $domQuery = '//div[@id="slogan"]/h2'; $domReturn = $xPath->query($domQuery); foreach($domReturn as $return) { $slogan = $return->nodeValue; echo "Child PID #" . $childPid . " says: " . $slogan . "\n"; } } $pids = array(); foreach ($hrefArray as $singleHref) { $pid = pcntl_fork(); if ($pid == -1) { die("Couldn't fork, error!"); } elseif ($pid > 0) { // We are the parent $pids[] = $pid; } else { // We are the child $childPid = posix_getpid(); doDomStuff($singleHref,$childPid); exit(0); } } foreach ($pids as $pid) { pcntl_waitpid($pid, $status); } // Clear the libxml buffer so it doesn't fill up libxml_clear_errors(); Which raises the following questions: 1) Given my hrefArray contains 4 urls - if the array was to contain say 1,000 product urls this code would spawn 1,000 child processes? If so, what is the best way to limit the amount of processes to say 10, and again 1,000 urls as an example split the child work load to 100 products per child (10 x 100). 2) I've learn that pcntl_fork creates a copy of the process and all variables, classes, etc. What I would like to do is replace my hrefArray variable with a DOMDocument query that builds the list of products to scrape, and then feeds them off to child processes to do the processing - so spreading the load across 10 child workers. My brain is telling I need to do something like the following (obviously this doesn't work, so don't run it): <?php libxml_use_internal_errors(true); ini_set('max_execution_time', 0); ini_set('max_input_time', 0); set_time_limit(0); $maxChildWorkers = 10; $html = new DOMDocument(); $html->loadHtmlFile('http://xxxx'); $xPath = new DOMXPath($html); $domQuery = '//div[@id=productDetail]/a'; $domReturn = $xPath->query($domQuery); $hrefsArray[] = $domReturn->getAttribute('href'); function doDomStuff($singleHref) { // Do stuff here with each product } // To figure out: Split href array into $maxChilderWorks # of workArray1, workArray2 ... workArray10. $pids = array(); foreach ($workArray(1,2,3 ... 10) as $singleHref) { $pid = pcntl_fork(); if ($pid == -1) { die("Couldn't fork, error!"); } elseif ($pid > 0) { // We are the parent $pids[] = $pid; } else { // We are the child $childPid = posix_getpid(); doDomStuff($singleHref); exit(0); } } foreach ($pids as $pid) { pcntl_waitpid($pid, $status); } // Clear the libxml buffer so it doesn't fill up libxml_clear_errors(); But what I can't figure out is how to build my hrefsArray[] in the master/parent process only and feed it off to the child process. Currently everything I've tried causes loops in the child processes. I.e. my hrefsArray gets built in the master, and in each subsequent child process. I am sure I am going about this all totally wrong, so would greatly appreciate just general nudge in the right direction.

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  • removing a line from a text file?

    - by Blackbinary
    Hi all. I am working with a text file, which contains a list of processes under my programs control, along with relevant data. At some point, one of the processes will finish, and thus will need to be removed from the file (as its no longer under control). Here is a sample of the file contents (which has enteries added "randomly"): PID=25729 IDLE=0.200000 BUSY=0.300000 USER=-10.000000 PID=26416 IDLE=0.100000 BUSY=0.800000 USER=-20.000000 PID=26522 IDLE=0.400000 BUSY=0.700000 USER=-30.000000 So for example, if I wanted to remove the line that says PID=26416.... how could I do that, without writing the file over again? I can use external unix commands, however I am not very familiar with them so please if that is your suggestion, give an example. Thanks!

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  • Reading and writing to SysV shared memory without synchronization (use of semaphores, C/C++, Linux)

    - by user363778
    Hi, I use SysV shared memory to let two processes communicate with each other. I do not want the code to become to complex so I wondered if I really had to use semaphores to synchronize the access to the shared memory. In my C/C++ program the parent process reads from the shared memory and the child process writes to the shared memory. I wrote two test applications to see if I could produce some kind of error like a segmentation fault, but I couldn't (Ubuntu 10.04 64bit). Even two processes writing non stop in a while loop to the same shared memory did not produce any error. I hope someone has experience concerning this matter and can tell me if I really must use semaphores to synchronize the access or if I am OK without synchronization. Thanks

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  • Sharing some info with all DLLs pulled into a process

    - by JBRWilkinson
    Hi all, We've got an Enterprise system which has many processes (EXEs, services, DCOM servers, COM+ apps, ISAPI, MMC snapins) all of which make use of many COM components. We've recently seen failures in some of the customer deployments, but are finding it hard to troubleshoot the cause. In order to track down the problem, we've augmented the entire source with logging statements where errors occur. In order to identify which logs came from what processes, the C++ logging code (compiled into all components) uses the EXE name to name the log. This is good for some cases, but not all - COM+ apps, ISAPI and MMC snapins all have system EXE names and the logs end up interleaved. I saw this post about shared data sections which might help, but what I don't understand is who decides what goes in the shared section. Is there any way I can guarantee that a particular piece of code writes into the shared section before anyone else reads it? Or is there a better solution to this problem?

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  • How do I view how many concurrent long polling requests there are on my server?

    - by Pascal
    My host is Joyent. My host says I have 15 process limit and prstat -J shows those processes but that doesn't tell me how many long polling requests are currently being served. I could record it myself but that would add alot of performance overhead. I need to know when the server is at its long polling limits. I know this limit occurs far before the memory or CPU is used up. From experimentation, I've already verified that the number of long polls open is NOT equivalant to the number of processes running, probably because each process has multiple threads, each serving a request. thanks.

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  • Threaded Django task doesn't automatically handle transactions or db connections?

    - by Gabriel Hurley
    I've got Django set up to run some recurring tasks in their own threads, and I noticed that they were always leaving behind unfinished database connection processes (pgsql "Idle In Transaction"). I looked through the Postgres logs and found that the transactions weren't being completed (no ROLLBACK). I tried using the various transaction decorators on my functions, no luck. I switched to manual transaction management and did the rollback manually, that worked, but still left the processes as "Idle". So then I called connection.close(), and all is well. But I'm left wondering, why doesn't Django's typical transaction and connection management work for these threaded tasks that are being spawned from the main Django thread?

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  • malloc hangs in Linux

    - by Rahul
    I am using Linux on a 16 G with 2 quad core CPU. There are 8 processes which are doing some work (CPU intensive/network i/o). Out of which 4 have a memory leak (These are test conditions so no problem in having leaks here). Total space is occupied by all processes is around 15.4 G only 200 MB is free in system. Things are fine for some hours. But after that malloc hangs (for a process which doesn't have a memory leak). Its stuck for for more than 4 minutes (Note CPU is not 100% but io has gone up signficantly). Now there is no problem in the hanged process. (It has not corrupted the memory). What malloc is doing? (is it tryibg to defragment or builidng up swap space).I am using SUSE 10. Any pointers?

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